LL-37 (5mg)
LL-37 (also known as CAP-18) is a 37-amino acid cationic antimicrobial peptide derived from the C-terminus of human cathelicidin (hCAP18). It is the only known human cathelicidin, exhibiting broad-spectrum antimicrobial activity and immunomodulatory properties. This protocol outlines a once-daily subcutaneous approach.
Reviewed by the AllPeptides.eu Editorial Team·Last reviewed: 2026-06-16
Educational information. Not medical advice, and no efficacy claim is implied. Regulatory approval is not a use recommendation by AllPeptides.eu.
⚠️ For informational/educational purposes only. Not medical advice. We do not sell any products. Self-treatment carries serious risks — consult a healthcare professional. Disclaimer
How It Works
LL-37 exerts both direct and indirect antimicrobial actions. Its amphipathic, cationic α-helical structure (net charge +6) allows for selective binding to and disruption of negatively charged microbial membranes. Beyond direct killing, it modulates host immunity: in murine sepsis models, it induced neutrophils to release microvesicles rich in antimicrobial proteins, reducing microbial load and improving survival. It can also bind bacterial LPS and block CD14/TLR4 interaction, reducing TNF release.
Quick Start
- Reconstitution: Add 3.0 mL bacteriostatic water → ~1.67 mg/mL concentration.
- Typical Daily Range: 100–400 mcg once daily (gradual titration).
- Storage: Lyophilized: freezer −20 °C; after reconstitution, refrigerator 2–8 °C for up to 4 weeks; avoid freeze-thaw.
Typical / Titration Approach (3 mL = ~1.67 mg/mL)
Route: Subcutaneous | Frequency: Once daily
| Week | Dose | Units (per injection) |
|---|---|---|
| Week 1 | 50 mcg | 3 Units (0.03 mL) |
| Week 2 | 100 mcg | 6 Units (0.06 mL) |
| Week 3 | 150 mcg | 9 Units (0.09 mL) |
| Week 4 | 200 mcg | 12 Units (0.12 mL) |
| Week 5 | 250 mcg | 15 Units (0.15 mL) |
| Week 6 | 300 mcg | 18 Units (0.18 mL) |
| Week 7 | 350 mcg | 21 Units (0.21 mL) |
| Week 8 | 400 mcg | 24 Units (0.24 mL) |
Studies report administration once daily subcutaneously. Some protocols use a 5-days-on, 2-days-off schedule.
Related compounds
Reconstitution Steps
- Draw 3.0 mL of bacteriostatic water.
- Inject slowly down the vial wall; avoid foaming.
- Gently swirl/rotate until dissolved (do not shake).
- Date and refrigerate at 2–8 °C, protecting from light.
Protocol Overview
- Goal: Support antimicrobial defense and healing processes.
- Schedule: Daily subcutaneous injections for 8–12 weeks (extendable to 16 wks).
- Storage: Lyophilized frozen; reconstituted refrigerated; avoid freeze-thaw.
Dosing Protocol
- Start: 50–100 mcg daily; increase by ~50 mcg weekly.
- Target: 200–400 mcg daily by Wk 4–8.
- Frequency: Once daily subcutaneously; optional 5-on/2-off.
- Cycle Duration: 8–12 weeks; optional extension to 16 wks.
- Timing: Consistent time; rotate sites.
- Break between cycles: After the cycle (8–16 weeks), a washout period of 4–6 weeks is recommended. LL-37 has immunomodulatory effects—the pause prevents dysregulation.
Washout & Cycle Restart
When can I restart?
After the cycle (8–16 weeks), a washout period of 4–6 weeks is recommended. LL-37 has immunomodulatory effects—the pause prevents dysregulation.
Minimum wait period: 4 weeks
Storage Instructions
- Lyophilized: Store at −20 °C in dry, dark conditions; stable ~24 months.
- Reconstituted: Refrigerate 2–8 °C for up to 4 weeks; frozen at −20 °C for up to 6 months.
- Allow vials to reach room temperature before opening.
Important Notes
Potential Benefits & Side Effects
Potential Benefits:
- In chronic venous leg ulcers, topical LL-37 treatment significantly accelerated healing rates.
- In trials of diabetic ulcers, LL-37 cream improved tissue granulation and wound closure.
- Broad-spectrum antimicrobial activity; in experimental sepsis, it reduced microbial loads and mortality.
- Generally well-tolerated; occasional mild injection site reactions.
Potential Side Effects:
- Injection site reactions (pain, redness, swelling).
- Transient flu-like symptoms (immune activation).
- Headache or mild fatigue (rare).
- Potential autoimmune activation at high doses (psoriasis, lupus).
- Cutaneous erythema with topical use (rare).
⚠️ Serious Warnings & Long-Term Risks
The following warnings are based on published literature, FDA labels, and post-marketing surveillance. They do not constitute medical advice. Consult a healthcare professional.
Dual role in oncogenesis
LL-37 (cathelicidin) has anti-cancer action in some tumors but pro-oncogenic in others (ovarian, lung, breast). May increase angiogenesis via VEGF and FGF-2.
📄 Peptides 2015Pro-inflammatory action at high doses
At high concentrations, LL-37 can activate mast cells, cause degranulation, and worsen inflammatory conditions (e.g., rosacea, psoriasis).
📄 Nat Med 2007References
- Wound Repair Regen (PMC, 2022) — LL-37 in healing hard-to-heal venous leg ulcers: a multicenter RCT
View Source - J Immunol (PMC, 2013) — Small peptide, big effects: the role of LL-37 in inflammation
View Source - Innate Immun (PMC, 2020) — LL-37 ameliorates sepsis via neutrophil-derived microvesicles
View Source - Arch Dermatol Res (PMC, 2023) — LL-37 cream in diabetic foot ulcers: RCT
View Source - PubMed (2010) — Vitamin D and the antimicrobial peptide cathelicidin (LL-37)
View Source
Recommended Supplements
Curcumin (Turmeric Extract)
Collagen Peptides
External Sources & Regulatory Status
Regulatory Approvals
Research-only — Endogenous antimicrobial peptide
Educational information. Not medical advice, and no efficacy claim is implied. Regulatory approval is not a use recommendation by AllPeptides.eu.
Continue Your Research
Explore tools and guides related to this protocol.
Important Disclaimer
The content of this website is provided exclusively for informational and educational purposes within the context of research literature.
Read the full Disclaimer →